While Jaker gave you what seems like a good alternative, there are a couple of things you may not realize.The Sacramento Airport is located at least 15 miles north of downtown Sacramento. Amtrak is located in Downtown, there are not many good public transportation options between the two. A cab ride is about $30.00-$40.00 ($4.00 flag drop then $4.00 a mile).If I may, a better option would be to take BART from San Francisco to the Richmond Station. Once in Richmond you can transfer to Amtrak to Sacramento. Bart and Amtrak share a station in Richmond.Once in Sacramento you can transfer to an Amtrak train to Redding.If you are flying into San Francisco you can catch BART right at the Airport.Or there are flights between San Francisco and Redding, in puddle jumpers, but the time and cost may make it worth it. Never mind the flying option, I just checked, from San Francisco you are looking at right around $500.00 round trip. From Sacramento you are looking at close to $700.00 round trip, and you have to fly from Sacramento, to San Francisco to catch a flight to Redding. No wonder the airlines are all bankrupt. I just checked on flight between San Francisco and Sacramento the cost there is real close to $300.00 round trip. United is the only airline that provides this service. The BART Amtrack option is less than $60.00 round trip.The Amtrak trip is quite comfortable, actually more so the flying and a lot less hassle.Enjoy your trip.
Sacramento is the closest airport. There is an Amtrak train from there to Redding.